OAKLAND — Minutes after BART union employees held a raucous rally and marched through downtown, union leaders issued a 72-hour notice that they may walk off their jobs at midnight Sunday.

The news came shortly after about 400 BART workers and their supporters, including actor Danny Glover, chanted for union solidarity, equal pay for minorities, women and older workers and an immediate contract.

“I came today to support the workers, because I think the workers should be able to have a decent contract,” said Marsha Feinland, a Berkeley resident and regular BART rider. “I hope that the management stops harassing the workers and decides to bargain in good faith.”

Several dozen people spoke in support of BART workers at Frank Ogawa Plaza on Thursday evening and in opposition of BART management and the failure to reach an agreement. Some said employees have made too many concessions.

“You can’t allow to be taken for granted and to continue to give up and give back,” Glover said. “We understand that if we concede, that we will continue to concede. … We have to stand up now, we make this work.”

If the unions and BART do not reach an agreement by midnight Sunday, it could result in the second shutdown of BART, consequently derailing more than 400,000 riders during the weekdays. BART management on July 2 last offered workers an 8 percent pay hike, with workers paying 10 percent to health care and 5 percent to their pensions, which workers say is unfair.

Following the rally, the crowd began to march several blocks to BART headquarters on Lakeside Drive, chanting: “What do we want? A contract. When do we want it? Now.” They also yelled in opposition of Thomas Hock, BART’s lead negotiator, who workers say has caused strikes in other locations in the past.

According to a public records search conducted by SEIU 1021, Hock has been involved in negotiations that have resulted in seven transit strikes since 2005.

When the crowd reached headquarters, holding signs and wearing shirts touting their cause, they started chanting: “Strike, strike, strike.”

The announcement of the strike notice was made in front of the Caltrans building, where the negotiations are being held.